Are you, or have you ever been, sick?

The New York Times has an article, briefly available here, that thoughtfully considers the following issue: Mental health authorities say that 50% of the population will develop mental disorders in their lives; so one must ask where mental health ends and illness begins. The article seems to address a sensible question unless you point out (as the article does not) that this emperor has no clothes.

If you started an article by mentioning that at some time in their lives, almost everyone will have a physical illness, no one would worry about whether that claim impinged on our perception of good physical health. The real issue underlying this article, which I believe it never mentions, is this: why is the diagnosis and treatment of non-physical illness so far behind the physical?

We have nearly scientific methods of diagnosing many of the physical illnesses, and pretty clear ways of deciding when some of them are cured. We can test for bacteria, white blood cells and antibodies. Most physical illnesses are routinely handled by one style of treatment. (In contrast, the Medpundit blog quotes Chekhov’s saying that "When many cures are offered for a disease, it means the disease is not curable." Most mental illnesses still have wide varieties of treatment.)
Diagnosis and treatment of mental illness seems to be a hundred years behind the standard for physical illness. When is it going to catch up? How is it going to catch up? When will we understand mental illness well enough that our perceptions of it will be more like our perceptions of physical illness?